Two-piece connector



May 16, 1967 u. TUCHEL 3,320,574

TWO-PIECE CONNECTOR Filed Feb. 4, 1964 3 Sheets-Sheet 1 SPOT WELD M INVENTOR FIG 3 Ulrich Tuchel ATTORNEYS y 16, 1967 u. TUCHEL 3,320,574

TWO-PIECE CONNECTOR Filed Feb. 4, 1964 5 Sheets-Sheet 2 15 I6 I8 25 2e F% G. H. 6 I INVENTOR Ulrich Tuchel Q /4 l '4 BY MW f 5 I I v ATTORNEYS y 6 u. TUCHEL 3,320,574

I NVENTOR Byw 'imw f w ATTORNEYS Ulrich Tuchel United States Patent 3,320,574 TWO-PIECE CONNECTOR Ulrich Tuchel, Neckartalstrasse 51, Heiibronn (Neckar), Germany Filed Feb. 4, 1964, Ser. No. 342,387 Claims priority, application Germany, Feb. 4, 1963, T 23,421 30 Claims. (Cl. 339-217) The present invention relates to a connector, particularly to an electrical plug-type cable connector for establishing multiple electrical connections in electric or electronic equipment, and which connector coacts with suitable single or multiple-pole contact carriers, for example, in the form of elongated insulated carriers, distributors, or special circuit units.

Modern plug-type connectors of this sort have to meet certain mechanical, electrical and physical requirements. For one thing, the connectors should be as small as possible. For another, the connectors should provide trouble-free and long-lasting electrical contact. Also, the contact resistance should remain constant over long periods of service. Moreover, the contact elements themselves should be such as to lend themselves to easy insertion into the contact carriers, the latter usually being in the form of supports or holders made of insulating material. The mounting of the contact elements in these insulating carriers should, on the one hand, be such that the contacts will not accidentally loosen themselves, while, on the other hand, the mounting should permit removal of the contact elements if such removal is desired. Furthermore, the connector asesmbly should be shock and vibration proof, as well as capable of functioning at elevated temperatures, i.e., the elastic spring elements should be fatigue-proof as well as substantially corrosion-proof, and also suitable for use in tropical climates. Finally, the cable connector has to be connectible to a lead or cable in any needed manner to obtain the necessary electrical and mechanical connection, for example, by soldering, clamping, clinching or otherwise deforming.

The design of conventional connectors considers primarily the mechanical requirements,and gives only incidental attention to the physical requirements made of electrical cable connectors. There exist plug-type contact elements with detent devices which can be snapped into a suitable receptacle, this type of connector having become increasingly common in recent times.

The contact elements of this type consist generally of resilient metallic strips which are so designed as to lend themselves to the simplest possible manufacturing techniques. Such connectors, however, were found to have the drawback that they failed to establish reliable contact for higher currents. Also, experience has shown that, once the contacts were placed into the insulated holder, they could thereafter not be removed without being damaged or without undergoing deformations which adversely affect their electrical characteristics. the contacts could no longer be relied upon for re-use, or, if no attention was paid to the damage which the contact elements might have undergone, the operability of the unit using the connector could be impaired. The latter, of course, carries with it expensive and time-consuming repairs. This problem is particularly acute if a given piece of equipment, e.g., a computer or control system, uses a large number of electrical connectors, because then there is a very high statistical probability that there will be some fault in the circuit. For very practical reasons, therefore, it becomes important that the contact elements be removable in order to allow them to be inserted properly.

It is, therefore, the primary object of the present inven- Consequently,

3,326,574 Patented May 16, 1967 tion to provide a connector which overcomes the above drawbacks and which has one or more of the following characteristic features:

Firstly, the contact is to be self-cleaning so as to avoid the natural corrosion which occurs when the contact element is made of base metal.

Secondly, the contact-making portion has electrical reserves in the sense that there are a plurality of paralle'ly connected contact points to provide the lowest possible contact resistance.

Thirdly, the elastic contact elements are so fashioned, and are provided with spring strips of such length, that, under the anticipated operating conditions, the fatiguelimit of the material will not be reached.

Founthly, the spring forces occurring upon insertion of the rigid contact element cooperating with the contact element according to the present invention are so balanced that, within the mutually eifective spring forces, there is sufiicient elasticity that mechanical vibrations of whatever frequency and amplitude will not adversely affect the electrical operability of the connector.

Fifthly, the contact element is provided, on the side at which another contact is to be inserted, with means which see to it that the position and operability of the electrically conductive spring elementswhich, as seen in the direction of insertion, are not reached immediately-will not be adversely affected even during rough handling and when the insertion takes place other than straight in.

Sixthly, relatively low contact resistance is obtained by providing a large number of parallely connected contact points, and hence a low contact resistance; furthermore, a large cross section is formed directly at the contact region, the arrangement being such that the abrasive action not only does not reduce the contact area but actually results in a larger contact area, thereby continuously improving the reliability of the contact during its life.

Seventhly, the arrangement of the connector is such that even if the two contact elements are accidentally separated from each other under load condition, arcing damage to the actual contact-making elements is, to a large extent, prevented.

Eighthly, the arrangement is such that the contact element can, without tools, easily be set into an insulating holder, the contact element mechanically detenting, i.e., locking, itself one or more times; the arrangement being, moreover, such that the contact element can be removed, without suffering any damage, so that it can thereafter again be used in other connectors.

Finally, the arrangement is such that the invention is applicable for use in all possible types of connectors, including miniature components.

With the above objects in view, the present invention resides in a contact member which is usable with an insulated holder having a receiving opening, one embodiment of which contact member is elongated and has consecutive first, second and third regions and includes two pieces. One of the pieces extends throughout the length of the contact member and hence through all of the regions and the other of the pieces is connected to the first piece and extends throughout the second and third regions; the first-mentioned piece is fashioned, in the first region, as a contact-making portion. Both pieces are fashioned, in the second region, as an anchoring portion for securing the contact member to the insulated holder, and, in the third region, as a lead-attaching portion at which a cable may be connected to the contact member. The second piece, in the second region, has a U-shaped part whose legs extend generally in the direction of the length of the contact member. and carry engaging means engageable on a shoulder of the receiving opening of the holder. The legs are in- The legs are resilient wardly resiliently deflectable thereby to permit insertion of the contact member into the opening, as well as to permit withdrawal of the contact member once it has been inserted.

Additional objects and advantages of the present invention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a rear view of a two-piece contact member according to the present invention.

FIGURE 2 is a side elevational view, partly in section, of the contact member of FIGURE 1.

FIGURE 3 is a front view of the contact member of FIGURES 1 and 2, part of one piece being cut away to facilitate illustration.

FIGURE 4 is a development of one of the two pieces.

FIGURE 5 is a sectional view showing the leadattaching portion of the contact member, the same being illustrated in conjunction with a cable.

FIGURE 6 is an end view of the contact member as seen in the direction of arrow A in FIGURE 1, FIGURE 6 showing, in section, a contact blade which has been inserted into the socket formed by the contact-making portion of the contact member.

FIGURE 7 is a fragmentary front view of more than one contact member and shows how individual contact members are connected to each other during machine assembly.

FIGURE 8 is a sectional view of an insulator holding two contact members according to the present invention. The contact member at the left of FIGURE 8 is shown in the fully inserted and locked position while the contact member at the right is shown in the partly inserted and not yet locked position.

FIGURE 9 is a development of the other of the two pieces.

FIGURE 10 is a fragmentary sectional view taken on line 101tl of FIGURE 9.

FIGURE 11 is a view similar to that of FIGURE 4 of a modified form of construction of the piece shown therein.

Referring now to the drawings, FIGURES 1, 2, 3, and 6, show one embodiment of an elongated contact member according to to the present invention, the same having what may be considered three distinct functional regions I, II and III along its length, namely, the actual contactmaking region I, the retaining or arresting region 11 which serves securely to lock the contact member to an insulating body or holder carrying the contact member, and the lead-connecting or terminal region III at which a cable is secured to the contact member. The contact member itself comprises two pieces A and B, the former being shown, in development, in FIGURE 4, and the latter being shown, in development in FIGURE 9. The piece A extends throughout the entire length, and hence throughout the three regions I, II and III, of the contact member, while piece B extends only through regions II and III. Each of the two pieces may be stamped from sheet metal.

'Region I, being the contact-making region, is constituted by the piece A which, in this region, is fashioned as a self-cleaning, safety-type multiple prong contact arranged, as best seen in FIGURES 1, 2, 3, and 6, to form a flat resilient socket for receiving a contact blade 16. FIGURE 8 shows such a contact blade carried by an insulating holder 32; FIGURE 8 also shows two contact members according to the present invention, both being carried by an insulator 12. The left-hand contact member is shown as having been fully inserted into insulator 12 and locked therein, while the right-hand contact member is shown but partly inserted, before the detent or locking mechanism-to be described belowhas come into operation.

The contact-making region I of piece A is provided with four back parts 1 which are resilient independently of each other, as well as two front parts 2 which are larger than the parts 1 and which are likewise resilient independently of each other.

The resilient tongues 1 and 2 form, in the direction of insertion of the blade 10, a second zone of the entire socket so that there is obtained a trouble-free and reliable contact between the socket and the blade. The cut-outs 3 serve for the self-cleaning of the contacts. The contact-making portion further comprises a ring-shaped part 4, which is reinforced by means of corrugations, this ringshaped part serving as a protector for the parts 1, 2, and, since it is located at the tip of the contact-making portion, constitutes the very first zone thereof. A slightly resilient ring-shaped portion 40, constituting a third zone of the socket, contributes to the over-all mechanical rigidity of the socket.

The piece A is provided with a strip-shaped continuation 11 integral and contiguous with the part of piece A forming the socket, this continuation 11 extending throughout the second region II. A still further stripshaped continuation 8, integral and contiguous with the first continuation 11, extends throughout the third region III.

The strip-shaped continuation 11 of piece A serves as a support for the piece B, the two pieces being suitably connected to each other, as, for example, by spot-welding or hard soldering. So much of the piece B which extends throughout region II constitutes the anchoring portion of the contact member as a whole. This anchoring portion has a U-shaped configuration and its legs 6- are provided with two lugs 5 which taper in the direction in which the contact member is inserted into the insulating holder 12 (FIGURE 8), this being the direction opposite to the direction in which the contact blade 10 is inserted into the socket formed by the contact-making portion of piece A. While FIGURE 1 and the upper part of FIGURE 3 show the lugs as tapering in the correct direction, FIG- URE 9which is a representation of piece B in development-shows the lugs 5 as tapering in the Opposite direction; the direction of taper, however, is reversed when the left-most part of piece B, as viewed in FIGURE 9, is bent over into the configuration depicted in FIGURES 1 to 3.

As illustrated in the case of the right-hand contact member of FIGURE 8, the lugs 5 are cammed to deflect inwardlyshown in phantom lines-when the contact member is inserted into the insulator 12. The lugs 5, being part of a resilient piece, come back to assume their original configuration after the contact member has been inserted. This is illustrated by the left-hand contact member of FIGURE 8 which shows the lugs 5 as being sea-ted on shoulders 13a formed within a widened portion 13 of the opening in the insulator 12 in which the contact member is received.

It will be noted that the U-shape (which should be considered and is intended to include what might be more accurately described as a V-shape) is taken in the plane of the flatness of the piece, thereby imparting to the legs the maximum resilient returning force.

Moreover, when the legs are in unstressed condition, i.e., not bent inwardly against their resiliency, their outer lateral edges extend substantially parallel to each other and are spaced from each other a distance which is adapted to the size of the opening of the holder 12, thereby to provide an approximate fit which guides the contact member into the opening.

If desired, the piece A may be provided with an additional locking strip 33 which seats on an inner shoulder of insulator 12.

The ends 7 of the legs 6 are provided with openings 7' arranged to receive a tool so that the legs 6 can be pressed in the plane of the U against the inherent resilience of the anchoring portion. This allows the contact member to be withdrawn from the insulator 12. The strip-shaped continuation 11 of piece A may be provided with cut-outs 14 which may be engaged by a suitable tool to allow the legs 6 to be pressed together from the side.

Instead of leaving the ends 7 fiat, they may be bent at right angles to the legs 6 to form upstanding flanges, as shown in FIGURES 2 and 3, so as to make it possible for a person to reach in from the outside and manually to press together the ends 7. If desired, a suitable tool can be provided, which may be in the nature of a pair of scissors without cutting edges, the ends of which scissors are provided with suitable projections or hooks adapted to engage the flanged ends 7 for pressing the same together, whereupon the scissors can be used to withdraw the contact member from the insulator 12.

Coming next to the region III, FIGURES 2, 3, 4, and 9 show the lead-attaching portion as consisting of crimped parts in the form of holding flanges 15 and 25 integral with piece B, these flanges forming, together with a tongue 8a of continuation 8 (see FIGURES 2 and 5) which is bent back to lie between the flanges, part of the actual cable-connecting portion in region III. The cable 16 is thus firmly contacted by the parts constituting region III, to form a good electrical and mechanical junction when the resilient tongue 8a is pressed together with the softer metal of which the holding flaps and the conductor 16 are made. The insulation of the cable is shown at 26.

In order to improve the mechanical connection between the cable and the contact member, at least two different holding flanges 15, 25, are provided, see FIGURES 5, 9 and 10. According to FIGURES 5 and 9, the flanges are provided with rib-like stampings forming protuberances 18 and 19. Instead of ribs 18, a slit 21 and holes 22 can be provided, as depicted in FIGURE 9.

FIGURE 5 also shows that the inner flaps 15 are specifically arranged to coact with the stripped end of cable 16, while theouter. flaps 25 are specifically arranged to coact with the insulation 26, as represented by the dif ferent dimensions of the two sets of flaps. Also, the edges of at least flaps 25 are provided with sharp teeth or serrations 20 so as to enable the flaps to penetrate the insulation and to makecontact with the conductive core of the cable proper, as well as to increase the mechanical strength of the cable-to-contact member junction. In the illustrated embodiment, however, the edges of flaps 15 are likewise provided with the serrations 20.

The flaps 25 are further provided with teeth which, after the cable has been rolled into the contact member, are bent interiorly of the contact member and bite into the cable. The specific arrangement of serrations, teeth, ribs, openings, etc., will, of course, depend on the desired mechanical and electrical characteristics.

As stated above, the pieces A and B lend themselves to being made by mass-punching techniques, e.g., by stamping or punching. In practice, a number of individual pieces can be made by a single stamping or punching operation, whereafter a set of pieces A can be combined with a set of pieces B. The necessary steps incident to soldering thepieces together, to bending the required portions, and to securing the different cable ends, can all be carried out for a large number of contact members simultaneously. As shown in FIGURE 7, the individual contact members are, during their manufacture and assembly, connected to each other by means of connecting webs 17 which can readily be removed from the contact members afterwards.

It will be understood that the above description of the present invention is susceptible to various modifications, changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

For example, the contact-making region I may, instead of being a resilient socket member, be fashioned as a rigid contact blade, i.e., be a male instead of a female type connector. Such a modified form of construction is shown in FIGURE 11 wherein the piece A is provided with a continuation 11' in the form of a male contact blade, the contacting portion thereof being indicated as constituting the region I of the assembled connector. Also, the terminal connection may be fashioned for the same purpose. Moreover, the contact member may be constituted by more than two punched pieces.

A connector according to the present invention lends itself to many difierent applications, as, for example, in conjunction with multiple circuit components, printed cir cuits, modules, and the like. In essence, thanks to the fact that the contact member comprises at least two connected together pieces and has a plurality of functional regions, with one of the pieces being effective in at least one of the regions and the other of the pieces being effective in at least one another of the regions, each of the pieces may be physically optimally adapted to carry out the function assigned to the respective regions.

Furthermore, the construction of the components of the present invention is such that they readily lend them selves to mass-production techniques, since all of the manufacturing steps, including the placing of the pieces in juxtaposition with each other, the cable insertion, and the bending and crimping operations may be fully automated.

Also, the two pieces may be made of the same material, or they may be made of different materials, each having the properties most suited to the task which the particular pieces are to carry out. For example, the piece A will be made of a material which provides the optimum electrical and mechanical contact, while the piece B will be made of a piece which affords the most reliable mechanical coupling between the contact member and the holder. Accordingly, the piece B may be made of a suitable plastic which is originally formed so that the portion thereof which corresponds to functional region II is folded over to have the form illustrated in FIG- URES 1 to 3 and the portion thereof corresponding to functional region III has the closed configuration shown in FIGURE 7. The plastic employed has a sufficient degree of resiliency to permit the arcuate portions of the flanges in region III to be resiliently spread apart for the insertion of a cable, these portions automatically springing back into a gripping condition when released. When piece B is made of a plastic, it will preferably be connected to piece A by means of a suitable cement applied at the points designating the spot welds in FIG- URES in 1 to 3 and the cable conductors will only be soldered to the tongue 8a of piece A.

Nor is the invention limited to the precise details of the contact-making portion shown in the above embodiment. For example, there can be a different number of contact fingers, or the socket may have a different configuration or, as stated above, be a male-type contact element. If the contact element is a socket, additional inwardly extending web-s, beads, and/ or flaps may be provided for increasing the number of contact points as well as the reliability of the mechanical connection, the actual dimensions of which webs, beads, etc., will be such as to provide the requisite tolerances. Any cut-outs or recesses can be modified to serve as inwardly directed spring arms.

The closed ring-shaped portion 4 which surrounds the axis of the socket, in addition to increasing the mechanical strength of the socket, also serves as an arc horn along which may propagate an are formed upon the removal of a contact from the socket. Scorching of the actual contact-making parts is thus prevented.

As for the lead-attaching portion, the fact that the same is provided with separate means, namely, the flaps 15 and 25, coacting with the bared cable end and the insulation of the cable, makes for a very strong and reliable connection. Moreover, the fact that the contact member does, in fact, coact not just with the bared cable but also with the insulation greatly improves the shock and vibration resistance of the contact mcmber.accord-,

ing to the present invention. This efiect is enhanced by making the flaps non-resilient so that the cable can be crim'ped or squeezed to the contact element.

Moreover, thanks to the fact that there is a mass of homogeneous material running between the cable and the actual contact-making portion, namely, the bent-over tongue 8a which is an integral part of piece A, makes for a reliable cable-to-contact connection whose resistance is not subject to changes due to corrosion of any welded parts, so that the conductivity of the contact member remains constant for long periods of time.

Finally, it is to be noted that, in the illustrated contact member according to the present invention, the points at which the actual electrical contact is made, namely, in the regions I and III, are located interiorly of the contact member so that these points are, or readily may be, protected against outside influences. The contact points are thus proof against mechanical and hand-infiicted damage.

What is claimed is:

1. For use with an insulated holder having a receiving opening, an elongated contact member having consecutive first, second and third regions, said contact member including two pieces, one of said pieces extending throughout the length of said contact member and hence throughout all of said regions and the other of said pieces being connected to said first piece and extending throughout said second and third regions; said one piece being, in said first region, a contact-making portion; said pieces being, in said second region, an anchoring portion for detachably securing said contact member to the insulated holder; said pieces being, in said third region, a lead-attaching portion at which a cable may be connected to the contact member.

2. A contact member as defined in claim 1, wherein said other piece, in said second region, has a U-shaped part whose legs extend generally in the direction of the length of said contact member, said legs being resilient and carrying engaging means engageable on a shoulder of the receiving Opening of the holder, said legs being inwardly resiliently deflectable thereby to permit insertion of the contact member into the opening.

3. A contact member as defined in claim 2 wherein said other piece is, in the zone of its U-shaped configuration, substantially flat, said U-shape being taken in the plane of the flatness, thereby imparting to said legs the maximum resilient returning force.

4. A contact member as defined in claim 2 wherein said legs are arranged to be accessible from the outside of the opening of the holder after said contact member has been inserted into the opening, thereby to permit the reaching of said legs to move the same together, hence to unseat said engaging means from said shoulder and to allow withdrawal of said contact member from the opening.

5. A contact member as defined in claim 2 wherein said engaging means comprise lugs extending transversely to the length of the contact member.

6. A contact member as defined in claim 5 wherein said lugs taper in the direction in which the contact member is insertable into the opening.

7. A contact member as defined in claim 2 wherein said legs, in unstressed condition, have outer lateral edges that extend substantially parallel to each other and that are spaced from each other a distance corresponding essentially to the size of the opening thereby to provide an approximate guiding fit for the contact member into the opening.

8. A contact member as defined in claim 2 wherein said other piece is made of sheet metal.

9. A contact member as defined in claim 2 wherein one piece is provided, in said second region, with a first stripshaped continuation contiguous with the part of said one piece which is in said first region, and, in said third region,

8 with a second strip-shaped continuation contiguous with said first strip-shaped continuation.

10. A contact member as defined in claim 9 wherein said other piece is provided, in said third region, with a strip-shaped continuation contiguous with the part of said other piece which is in said second region, said stripshaped continuation of said other piece overlying said second strip-shaped continuation of said one piece.

11. A contact member as defined in claim 10 wherein said pieces are permanently secured to each other in said second region of the contact member.

12. A contact member as defined in claim 11 wherein said pieces are in electric contact with each other.

13. A contact member as defined in claim 11 wherein said contact-making portion of said one piece is a male contact element.

14. A contact member as defined in claim 11 wherein said contact-making portion of said one piece is a female contact element.

15. A contact member as defined in claim 14 wherein said contact element is a socket having a plurality of contact points with which to engage a male contact element inserted into said socket.

16. A contact member as defined in claim 15 wherein said contact element forms a flat socket and is provided with two sets of opposite contact fingers, said contact fingers being resilient independently of each other.

17. A contact member as defined in claim 16 wherein the contact fingers on one side are larger than those on the other.

18. A contact member as defined in claim 16 wherein said contact-making portion has at least one piece forming a substantially completely closed entity surrounding the axis of said socket for imparting increased mechanical rigidity to said socket.

19. A contact member as defined in claim 1 wherein said lead-attaching portion comprises means for receiving a stripped cable end and further means for receiving an insulated cable section immediately adjacent the stripped cable end.

20. A contact member as defined in claim 19 wherein each of said means comprises at least two flaps bent about a cable connected to said contact member.

21. A contact member as defined in claim 20 wherein the contact element, in the vicinity of said flaps, is provided with rib-1ike protuberances.

22. A contact member as defined in claim 1 wherein said lead-attaching portion is provided with inwardly extending means providing an abutment adapted to be engaged by a cable end inserted into said lead-attaching portion.

23. A contact member as defined in claim 1 wherein said lead-attaching portion is provided with inwardly extending means for penetrating insulation of a cable inserted into said lead-attaching portion.

24. A contact member as defined in claim 20 wherein said flaps are provided with serrated edges. 7

25. A contact member as defined in claim 1 wherein said part of said one piece is in direct electrical contact with a lead inserted into said lead-attaching portion, thereby to provide a continuous electrical connection, of homogeneous material, between the cable and said contactmaking portion.

26. A contact member as defined in claim 25 wherein said part of said one piece is a spring tongue.

27. A contact member as defined in claim 1 wherein a cable is attached to said lead-attaching portion by crimp- 28. A contact member as defined in claim 1 wherein said two pieces are stamped from a single piece.

29. A connector comprising, in combination:

(a) an insulated holder having a receiving opening;

and

(b) an elongated contact member arranged in said opening and having consecutive first, second and third regions, said contact member including two pieces, one of said pieces extending throughout the length of said contact member and hence throughout all of said regions and the other of said pieces being connected to said first piece and extending throughout said second and third regions; said one piece be ing, in said first region, a contact-making portion; said pieces being, in said second region, an anchoring portion for detachably securing said contact member to the insulated holder; said pieces being, in said third region, a lead-attaching portion at which a cable may be connected to the contact member.

30. A connector as defined in claim 29 wherein said receiving opening is provided with a shoulder and wherein said other piece of said contact member, in said second region, has a U-shaped part Whose legs extend generally in the direction of the length of said contact member, said legs being resilient and carrying engaging means engaging said shoulder of said opening of said holder, said legs being inwardly resiliently deflectable thereby to permit withdrawal of said contact member from said opening.

References Cited by the Examiner UNITED STATES PATENTS Fulton 339-223 Liss.

Shore 339258 Parker 339223 X Hackbarth 33997 Buchanan 339276 Watts 339217 Heath 339-220 Tuchel 339-258 Berg 339-276 Bucher et a1 339'223 Mavity 339276 X Batcheller 339-276 Macnamara 339-276 X Scheller 229217 X 20 MARVIN A. CHAMPION, Primary Examiner.

E. C. ALLEN, P. A. CLIFFORD, Assistant Examiners. 

1. FOR USE WITH AN INSULATED HOLDER HAVING A RECEIVING OPENING, AN ELONGATED CONTACT MEMBER HAVING CONSECUTIVE FIRST, SECOND AND THIRD REGIONS, SAID CONTACT MEMBER INCLUDING TWO PIECES, ONE OF SAID PIECES EXTENDING THROUGHOUT THE LENGTH OF SAID CONTACT MEMBER AND HENCE THROUGHOUT ALL OF SAID REGIONS AND THE OTHER OF SAID PIECES BEING CONNECTED TO SAID FIRST PIECE AND EXTENDING THROUGHOUT SAID SECOND AND THIRD REGIONS; SAID ONE PIECE BEING, IN SAID FIRST REGION, A CONTACT-MAKING PORTION; SAID PIECES BEING, IN SAID SECOND REGION, AN ANCHORING PORTION FOR DETACHABLY SECURING SAID CONTACT MEMBER TO THE INSULATED HOLDER; SAID PIECES BEING, IN SAID THIRD REGION, A LEAD-ATTACHING PORTION AT WHICH A CABLE MAY BE CONNECTED TO THE CONTACT MEMBER. 